Spin-spin relaxation of protons in ferrofluids characterized with a high-T c superconducting quantum interference device-detected magnetometer in microtesla fields
Journal
Applied Physics Letters
Journal Volume
100
Journal Issue
23
Date Issued
2012
Author(s)
Liao, S.-H.
Liu, C.-W.
Yang, H.-C.
Chen, H.-H.
Chen, M.-J.
Chen, K.-L.
Horng, H.-E.
Yang, S.-Y.
Abstract
In this work, the spin-spin relaxation of protons in ferrofluids is characterized using a high-Tc SQUID-based detector in microtesla fields. We found that spin-spin relaxation rate is enhanced in the presence of superparamagnetic nanoparticles. The enhanced relaxation rates are attributed to the microscopic field gradients from magnetic nanoparticles that dephase protons’ spins nearby. The relaxation rates decrease when temperatures increase. Additionally, the alternating current magnetic susceptibility was inversely proportional to temperature. Those characteristics explained the enhanced Brownian motion of nanoparticles at high temperatures. Characterizing the relaxation will be helpful for assaying bio-molecules and magnetic resonance imaging in microtesla fields.
SDGs
Type
journal article